You need to configure Cisco Unity Connection in a cluster that will have four servers. One server will hold the publisher role. How many licenses do you need to configure Cisco Unity Connection…

A single license covers only one server and cannot support a cluster, which by definition requires at least two licensed nodes.

Cisco Unity Connection high availability clustering is architecturally limited to a two-node topology consisting of one publisher and one subscriber server. Because the cluster can contain only two servers, exactly two Unity Connection server licenses are required - one for each node. Any scenario describing more than two nodes exceeds the supported Unity Connection cluster topology, making two the correct and sufficient license count.

Three licenses are unnecessary because Unity Connection's maximum supported cluster size is two servers, leaving a third license with no node to assign it to.

Four licenses would imply a four-node cluster, which is not a supported or valid topology for Cisco Unity Connection.

Five licenses far exceed the two-server maximum for a Unity Connection cluster and have no valid use in this context.

Six licenses are completely outside the scope of Unity Connection clustering, which is strictly limited to two nodes.